Polyphenyl ether compositions



United States Patent 3,423,469 POLYPHENYL ETHER COMPOSITIONS Roger E.Hatton, Kirkwood, Mo., and Louis R. Stark,

East St. Louis, lll., assignors to Monsanto Company,

a corporation of Delaware No Drawing. Filed Apr. 30, 1962, Ser. No.191,337 US. Cl. 260-6115 13 Claims Int. Cl. C07c 41/12, 43/22 Thisinvention relates to polyphenyl ether compositions having improvedoxidative stability. More particularly, this invention relates topolyphenyl ethers stabilized against oxidative degradation by theincorporation therein of certain organolead compounds.

The polyphenyl ethers are compounds known to the art. It has beenproposed to use the polyphenyl ethers as gas turbine (jet) enginelubricants, as hydraulic fluids, as electronic equipment coolants, asatomic reactor coolants, as diffusion pump fluids, etc., since theypossess many desirable properties such as high and low temperaturestability, foam resistance and good storage stability, even where thetemperatures encountered range up to 700 F. and higher. Because of theirgood balance of properties, the polyphenyl ethers have recently beenreceiving increasing consideration as lubricants for jet engines.However, as the speed and altitude of operation of jet engine-containingvehicles increases, lubrication problems also increase because ofincreased operating temperatures and higher bearing pressures resultingfrom the increased thrust needed to obtain higher speeds and altitudes.As the service conditions encountered become increasingly severe, theuseful life of the polyphenyl ethers is shortened, primarily due totheir deficiency in oxidative stability above 500 F.

The useful life of a lubricant can be adjudged on the basis of manycriteria, such as the extent of viscosity increase, the extent ofcorrosion to metal surfaces in contact with the lubricant, and theextent of deposit formation. Those skilled in the art have found manyways to improve lubricants and to thereby retard or prevent the effectswhich shorten their useful lives. Thus, it is a general practice to addsmall amounts of other materials, or additives, to lubricants in orderto affect their properties. It is difificult, however, especially asoperating temperatures are increased, to find additives which willperform the function for which they are added and yet not interjectother problems, such as increasing corrosion and engine deposits.

It has now been found that the oxidative stability, and thus the usefullife of the polyphenyl ethers, can be greatly extended, even under thesevere conditions encountered in jet engines and other devices operatingat temperatures of the order of 600 F. and higher, by the addition topolyphenyl ethers of an organolead compound.

It is therefore an object of this invention to provide polyphenyl ethercompositions having increased resistance to oxidation. A further objectis to improve the viscosity stability of polyphenyl ether compositions.A still further object is to provide polyphenyl ether compositionshaving increased color stability.

The objects mentioned above and others, which will hereinafter beapparent, are accomplished by adding to the polyphenyl ethers anorganolead compound selected from (a) phenyl lead compounds representedby the structural formula, (Ph) -Pb-(X) where Ph is phenyl, X ishalogen, and m is a whole number from 1 to 4, and (b) lead acidderivatives represented by the structural formula,

Pb O( iR 3,423,469 Patented Jan. 21, 1969 where R is an alkyl or aphenyl, and y is selected from 2 and 4.

Examples of compounds falling within the definition above are, in (a)tetraphenyllead, triphenyllead chloride, triphenyllead fluoride,diphenyllead dichloride, diphenyllead diiodide, phenyllead trichloride,and diphenyllead dibromide; and, in (b) lead benzoate, lead vanillate,lead tetraacetate, lead acetate, lead ethylcaproate, lead ethylhexoate,lead 2-ethylhexanoate, lead naphthenate, lead octoate, lead oleate, leadoxalate, lead palmitate, lead tungstate, lead vanadate, lead salicylate,lead stearate, lead subacetate, and lead tallate.

Generally, the phenyllead compounds of this invention can be prepared bythe action of a Grignard reagent on lead chloride, and lead acidderivatives can be prepared by salt exchange, neutralization, etc., asfrom salts of sodium benzoate or acetate and lead chloride.

The polyphenyl ethers to which this invention pertains can berepresented by the structure,

F A l UL L in where n is a Whole number from 2 to 5. The preferredpolyphenyl ethers are those having all of their ether linkages in themeta position, since the all-meta-linked ethers are the best suited formany applications because of their wide liquid range and high degree ofthermal stability. However, mixtures of polyphenyl ethers (i.e., eitherisomeric mixtures or mixtures of homologous ethers) can also be used toobtain certain properties; e.g., lower solidification points. Examplesof the polyphenyl ethers contemplated are the bis(phenoxyphenyl)ethers,e.g. bis(mphenoxyphenyl)ether; the bis( phenoxyphenoxy)benzenes, e.g.,m-bis(m-phenoxyphenoxy)benzene, m -bis(p-phenoxyhenoxy)benzene, obis(o-phenoxyphenoxy)benzene; the bis(phenoxyphenoxyphenyl)ethers, e.g.,bis[m- (mphenoxyphenoxy)phenyl]ether, bis[p (p henoxyphenoxy) phenyl]ether, m- (m-phenoxyphenoxy) (o-phenoxyphenoxyphenoxy)phenyHether, bis[p(p phenoxyphenbenzenes, e.g., m bis [m (m-phenoxyphenoxy)phenoxy]benzene, p-bis [p- (rn-phenoxyphenoxy phenoxy] benzene,m-bis[m-p-phenoxyphenoxy)phenoxyjbenzene. It is also contemplated thatmixtures of the polyphenyl ethers can be used. For example, mixtures ofpolyphenyl ethers in which the non-terminal phenylene rings (i.e., thoserings enclosed in the brackets in the above structural representationsof the polyphenyl ethers contemplated) are linked through oxygen atomsin the metaand para-positions, have been found to be particularlysuitable as lubricants because such mixtures possess lowersolidification points and thus provided compositions having wider liquidranges. Of the mixtures having only metaand paralinkages, a preferredpolyphenyl ether mixture of this invention is the mixture of five-ringpolyphenyl ethers where the non-terminal phenylene rings are linkedthrough oxygen atoms in the metaand para-positions and composed, byweight, of 65% m-bis(m-phenoxyphenoxy) benzene, 30% m [(mphenoxyphenoxy)(p phenoxyphenoxy) jbenzene, and 5% m bis(pphenoxyphenoxy) benzene. Such a mixture solidifies at about lO F.,whereas the three components solidify individually at temperatures abovenormal room temperatures.

The aforesaid polyphenyl ethers can be obtained by the Ullmann ethersynthesis which broadly relates to ether-forming reactions of, forexample, alkali metal phenoxides such as sodium and potassium phenoxideswith aromatic halides such as bromobenzene in the presence of a coppercatalyst such as metallic copper, copper hydroxides, or copper salts.

The major bench scale method used for evaluating the oxidative stabilityof a lubricant is the Procedure given in Federal Specification 791,Method 5308.4, according to which the lubricant to be tested is heatedat a specified temperature in the presence of certain metals and oxygen,and the viscosity increase of the lubricant is determined. Additionally,information as to the corrosivity of a lubricant to metals can beobtained.

Various polyphenyl ether compositions were tested according to theprocedure of Federal Specification 791, Method 5308.4, except that thetemperature was held at 600 F. instead of 250 F. as specified in thatprocedure, and the metal specimens used were steel, copper, silver,titanium, magnesium alloy, and aluminum alloy. The compositions testedhad essentially no elfect on steel, titanium and aluminum alloy, andgenerally showed a slight increase in copper corrosion. In some tests,no metal specimens were included and only the viscosity increase wasmeasured. The results observed using the above-described procedure arerecorded in the table below. Viscosity measurements were made accordingto ASTM Method D-445-5 3T using a Cannon-Fenske modified Ostwaldviscosimeter. The percentage of viscosity increase was determined bytaking the difference in viscosity of a composition before and after itwas heated, dividing that difierence by the original viscosity, andmultiplying the quotient by 100. The corrosivity to metals wasdetermined by weighing the metal specimens before and after the test.The base stock used was composed, by Weight, of about 65%m-bis(m-phenoxyphenoxy)benzene, about 30% m-[(m-phenoxyphenoxy)(p-phenoxyphenoxyfl benzene, and about 5%m-bis(p-phenoxyphenoxy)benzene.

organolead compound as described above. Since the amount of organoleadcompound added above the minimum amount mentioned has little or noeffect on the degree of stabilization obtained, considerations otherthan stabilization have to be taken into account in selecting thequantity of organoleadcompound to be added to a particular polyphenylether. As a practical matter, about 5% by weight of an organoleadcompound is the maxi-mum amount to be used, although it is preferred touse from about 0.05% to about \1% by Weight, since, within that range ofconcentrations, the amount of additive used is low enough so thatsolubility considerations are not limit ing, yet there is no significantdifference in the degree of stabilization obtained. Because of thevarious considerations which go into the choice of the amount oforganolead compound used and also because of the slight differencesexisting between various polyphenyl ethers and mixtures thereof, theamount of organolead compounds can be expressed as a stabilizing amount;i.e., an amount which is effective to provide an increase in theoxidative stability of the polyphenyl ether compositions contemplated.

It is also contemplated that other additives, such as pour pointdepressants, crystallization. suppressants, viscosity index improvers,dyes, rust inhibitors and materials to improve extreme pressureproperties, can be added to the compositions of this invention.

Other modes of applying the principles of this invention will beapparent to those skilled in the art. Accordingly, while this inventionhas been described with reference to various specific examples andembodiments, it is understood that the invention is not limited to suchexamples Organolead compound Viscosity Inc.,

Weight change,

Composi- Percent mg. per sq. cm. tion No.

Description Percent 100 F. 210 F. Mg. Ag.

by Wt.

1 38 1 38 1 41 2 414 No metals .0 18 0.14 0. 34 0 17 0. 47 0. 39 1.011 1. 6 0.02 0. 5 12 No metals 7. 0.2 16 0.10 0.16 8. 0.5 12 No metals9. 0.5 16 .12 10 0.2 11 No metals 0. 5 63 23 -0. 78 0. 12 do..." 0.5 16No metals Diphenyllead Diehloride.. 0.5 17 -2. 02 0.34 14 do 0.5 47 12No metals 1 Average of 16 separate tests representing 3 lots of basefluid. 2 Average of 7 separate tests representing 3 lots of base fluid.

From the above, it is clearly evident that the addition of an organoleadcompound to the polyphenyl ethers provides polyphenyl ether compositionshaving a greatly in- 5 creased oxidative stability and, therefore, agreatly extended useful life. In regard to the extension of useful life,it has been found that the test procedure described above correlatesquite well with the results obtained under full-scale aircraft gasturbine-bearing tests and under conditions of actual use. It has beenfound that the magnitude of change in the viscosity at 100 F., asmeasured by the test procedure, is representative of the extent ofincreased service life obtainable under actual conditions.

It is also evident from the data presented above that the addition of anorganolead compound to the polyphenyl ether provides polyphenyl ethercompositions having significantly reduced rates of corrosion to certainmetals and reduced varnishing. It was also noted, by visual inspection,that the organolead stabilized polyphenyl ethers had significantly lesssludge than did the unstabilized polyphenyl ethers.

The improved polyphenyl ether compositions of this invention can beobtained by the addition to the polyphenyl ethers of at least about0.01% by weight of an and that it may be variously practiced Within thescope of the following claims.

What is claimed is:

1. A composition comprising (a) a polyphenyl ether represented by thestructural wherein n is a whole number from 2 to 5, and (b) astabilizing amount of an organolead compound selected from the groupconsisting of (l) phenyllead compounds represented by the structuralformula, (Ph) Pb-(X) where Ph is phenyl, X is halogen, and m is a wholenumber from 1 to 4, and

(2) lead acid derivatives represented by the structural formula,

i Pb0 -R where R is alkyl or phenyl, and y is selected from 2 and 4. 2.A composition comprising (a) a polyphenyl ether represented by thestructural formula,

OLQ OL L 1 where n is a whole number from 2 to 5, and

(b) a stabilizing amount of a phenyllead compound represented by thestructural formula,

where P11 is phenyl, and m is a whole number from 1 to 4.

3. A composition comprising (a) a polyphenyl ether represented by thestructural formula,

(Lg OL J11 where n is a whole number from 2 to 5, and (b) a stabilizingamount of tetraphenyllead. 4. A composition comprising (a) a polyphenylether represented by the structural formula,

6 where R is alkyl or phenyl, and y is selected from 2 and 4.

6. A composition comprising (a) a mixture of fixe-ring polyphenyl etherswherein the non-terminal phenylene radicals are linked through oxygen inthe meta-and para-positions, and

(b) a stabilizing amount of tetraphenyllead.

7. A composition comprising (a) a mixture of five-ring polyphenyl etherswherein the non-terminal phenylene radicals are linked through oxygen inthe metaand para-positions, and

(b) a stabilizing amount of lead benzoate.

8. A composition comprising (a) a mixture of five-ring polyphenyl ethershaving, by

weight, about m-bis (m-phenoxyphenoxy)benzene, 30% m [(m phenoxyphenoxy)(p phenoxyphenoxy)]benzene, and 5% m-bis(p-phenoxyphenoxy)benzene, and

(b) a stabilizing amount of tetraphenyllead.

9. A composition comprising (a) a mixture of four-ring polyphenylethers, and

'(b) a stabilizing amount of tetraphenyllead.

10. A composition comprising (a) a mixture of four-ring polyphenylethers, and

(b) a stabilizing amount of lead benzoate.

11. A composition comprising 21) bis [m-(m-phenoxyphenoxy) phenyl ether,and

(b) a stabilizing amount of tetraphenyllead.

12. A composition comprising (a) a seven-ring polyphenyl ether, and

('b) a stabilizing amount of tetraphenyllead.

13. A composition comprising (a) a four-ring polyphenyl ether, and

(b) a stabilizing amount of tetraphenyllead.

References Cited UNITED STATES PATENTS 2,307,090 1/1943 Yngue 260-45752,679,459 5/1954 Rosenwald 260611.5 XR 2,711,401 6/1955 Lally 26045.752,720,544 10/1955 Mallinckrodt et a1. 260-611.5 2,720,546 10/1955Mallinckrodt et al. 260611.5 2,181,914 12/1939 Rosen 252-464 2,940,9296/1960 Diamond 260613 XR 2,354,218 7/1944 Murray 252-377 XR 2,681,8916/1954 Bas et a1 25232.7 XR 2,813,076 11/1957 Edelmar et a1 252 XR3,244,627 4/ 1966 Smith 252-611.5 XR

BERNARD HELFIN, Primary Examiner.

U.S. Cl. X.R.

1. A COMPOSTION COMPRISING (A) A POLYPHENYL ETHER REPRESENTED BY THESTRUCTURAL FORMULA,